Children as young as 11 are writing malicious software to steal credit card information from online gamers simply because they can.

Computer security software maker AVG Technologies said it had evidence of an 11-year-old Canadian child who had done such a thing.

AGV chief technology officer Yuval Ben-Itzhak said the code usually took the form of a basic Trojan written using the .NET software framework for computers running the Windows operating system.

"What is the motivation for this behaviour? Most probably these child script writers are not doing it for financial gain, but more likely for a thrill. . . . It is also logical to assume that at least some of those responsible will be tempted to experiment with much more serious cyber-crimes."

Paul Matthews, chief executive of the Institute of IT Professionals in New Zealand, said numbers of "script kiddies" - younger hackers using toolkits provided by others - appeared to be on the rise.

"Most malware has historically been created for non-financial purposes, generally between individual hackers and groups to boost standing in their community or for social reasons. The exception has been in more recent times when organised criminals and in some cases governments have taken to hacking."

Gorilla Technology's Paul Spain, of the NZ Tech Podcast, said anyone with good technical knowledge could potentially create a new virus or piece of malware.

"These [malware and virus] toolkits typically make use of known security issues across common computing platforms.

"As Windows has become more secure in recent years, less secure software that many Windows and Mac users rely on such as the Oracle Java, Adobe Flash and Adobe Reader have become the biggest targets."